Expulsion and impeachment are two different things, and two different procedures. As I said yesterday, the issue was that Psalm 144 had said Cruz ought to be impeached.
As for expulsion, so far, at least two courts, including the Pennsylvania Supreme Court, have said that Cruz is qualified to be President, which means that he is considered by those courts to be a U. S. citizen, and even a natural born citizen. Those cases would be an extremely high hurdle for the Senate to get over before they could expel him.
BTW, I believe that Cruz is not an NBC, but that after two terms of Obama without one court case that was allowed to be heard all the way through to a decision, that is apparently no longer a problem for candidates to overcome.